Leases and Aircraft Maintenance Deposits

The Company leases various types of equipment and property, primarily aircraft, spare engines and airport facilities under leases, which expire in various years through 2032. Lease terms are generally 12 to 18 years for aircraft and up to 30 years for other leased equipment and property.

Total rental expense for all leases charged to operations for the years ended 2016, 2015 and 2014 was $283.9 million, $282.7 million and $254.3 million, respectively. Total rental expense charged to operations for aircraft and engine operating leases for the years ended December 31, 2016, 2015 and 2014 was $201.7 million, $211.5 million and $195.8 million, respectively. Supplemental rent is made up of maintenance reserves paid or expected to be paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and probable return condition obligations. The Company expensed $9.0 million, $7.7 million and $7.5 million of supplemental rent recorded within aircraft rent during 2016, 2015 and 2014, respectively.

Some of the Company’s master lease agreements provide that the Company pays maintenance reserves to aircraft lessors to be held as collateral in advance of the Company’s required performance of major maintenance activities. Substantially all of these maintenance reserve payments are calculated based on a utilization measure, such as flight hours or cycles, while some maintenance reserve payments are fixed contractual amounts. Fixed maintenance reserve payments for these aircraft and related flight equipment, including estimated amounts for contractual price escalations, are expected to be $7.7 million in 2017, $7.0 million in 2018, $5.7 million in 2019, $5.4 million in 2020, $5.5 million in 2021, and $17.7 million in 2022 and beyond. These lease agreements provide that maintenance reserves are reimbursable to the Company upon completion of the maintenance event in an amount equal to either (1) the amount of the maintenance reserve held by the lessor associated with the specific maintenance event or (2) the qualifying costs related to the specific maintenance event. Some of the master lease agreements do not require that the Company pay maintenance reserves so long as the Company's cash balance does not fall below a certain level. As of December 31, 2016, the Company is in full compliance with those requirements and does not anticipate having to pay reserves related to these master leases in the future.

At lease inception and at each balance sheet date, the Company assesses whether the maintenance reserve payments required by the master lease agreements are substantively and contractually related to the maintenance of the leased asset. Maintenance reserve payments that are substantively and contractually related to the maintenance of the leased asset are accounted for as maintenance deposits to the extent they are expected to be recoverable and are reflected as aircraft maintenance deposits in the accompanying balance sheets. The Company makes certain assumptions to determine the recoverability of maintenance deposits. These assumptions are based on various factors such as the estimated time between the maintenance events, the date the aircraft is due to be returned to the lessor, the cost of future maintenance events and the number of flight hours the aircraft is estimated to be utilized before it is returned to the lessor. When it is not probable the Company will recover amounts currently on deposit with a lessor, such amounts are expensed as supplemental rent. The Company expensed $2.2 million, $2.3 million and $1.6 million of paid maintenance reserves as supplemental rent during 2016, 2015 and 2014, respectively.

As of December 31, 2016 and 2015, the Company had short-term and long-term aircraft maintenance deposits of $286.4 million and $279.9 million, respectively, on its balance sheets. The Company has concluded that these aircraft maintenance deposits are probable of recovery primarily due to the rate differential between the maintenance reserve payments and the expected cost for the related next maintenance event that the reserves serve to collateralize.

The Company’s master lease agreements also provide that some maintenance reserves held by the lessor at the expiration of the lease are nonrefundable to the Company and will be retained by the lessor. Consequently, any usage-based maintenance reserve payments after the last major maintenance event are not substantively related to the maintenance of the leased asset and therefore are accounted for as contingent rent. Supplemental rent is recorded at the time a non-refundable maintenance reserve

payment is made that has been substantively determined to be contingent rent.

As of December 31, 2016, the Company had a fleet consisting of 95 A320 family aircraft. As of December 31, 2016, the Company owned 36 of these aircraft and financed 59 aircraft under operating leases with expirations between 2017 and 2029. In addition, as of December 31, 2016, the Company had 11 spare engines financed under operating leases with lease term expiration dates ranging from 2018 to 2027 and owned 1 spare engine. Two of the Company's leased aircraft have variable rent payments, which fluctuate based on changes in LIBOR (London Interbank Offered Rate). The Company entered into sale leaseback transactions with third-party aircraft lessors for the majority of these aircraft and engine leases. Deferred losses resulting from these sale leaseback transactions are included in other long-term assets on the accompanying balance sheet. Deferred losses are recognized as an increase to rent expense on a straight-line basis over the term of the respective operating leases. Deferred gains are included in deferred gains and other long-term liabilities on the accompanying balance sheet. Deferred gains are recognized as a decrease to rent expense on a straight-line basis over the term of the respective operating leases.

During the twelve months ended December 31, 2016, the Company took delivery of 11 aircraft under secured debt arrangements, purchased 7 previously leased aircraft and entered into a direct lease agreement with a third-party lessor for 5 A320neos. In addition, the Company purchased one spare engine. All of the Company's aircraft and engine leases are accounted for as operating leases. Under the terms of the lease agreements, the Company will continue to operate and maintain the aircraft. Payments under the lease agreements are fixed for the term of the lease. The lease agreements contain standard termination events, including termination upon a breach of the Company's obligations to make rental payments and upon any other material breach of the Company's obligations under the leases, and standard maintenance and return condition provisions. Upon a termination of the lease due to a breach by the Company, the Company would be liable for standard contractual damages, possibly including damages suffered by the lessor in connection with remarketing the aircraft or while the aircraft is not leased to another party.

Future minimum lease payments under noncancellable operating leases with initial or remaining terms in excess of one year at December 31, 2016 were as follows:



	Operating Leases
	Aircraft and Spare Engine Leases		Property Facility Leases		Total Operating Leases
	(in thousands)
2017	$	218,484	$	39,189	$	257,673
2018	203,465		38,048		241,513
2019	184,566		30,451		215,017
2020	176,590		18,928		195,518
2021	166,967		8,969		175,936
2022 and thereafter	558,038		53,734		611,772
Total minimum lease payments	$	1,508,110	$	189,319	$	1,697,429